A robot is a machine or device capable of operating automatically, which may operate either according to a person's instruction or according to a pre-programmed program. The robot can operate in place of a person and can operate with a high work efficiency and stable work quality. Hence, robotics is extensively applied to fields such as production, architecture and manufacture. For example, during manufacture of a liquid crystal panel, a robot may perform work such as transportation of substrates in place of people.
The robot usually comprises a base and arms secured to the base. The robot usually accomplishes transportation of an article by virtue of the arms, which are usually in a horizontal state. Over time, the robot's arms inevitably sag so that the robot cannot operate as effectively. Slight sag usually cannot be directly observed via naked eyes. Therefore, a levelness detecting device needs to be used to detect the levelness of the arms. In the prior art, usually a levelness measuring instrument is employed to detect the levelness of the robot's arms. The robot usually comprises a first arm and a second arm, the upper surfaces of which are usually coplanar and parallel to a horizontal plane. Specifically, the levelness measuring instrument is placed at a position at a preset distance from the robot, and the position of the levelness measuring instrument is kept the same during the detection. First, a ruler is placed at a front end of the first arm in a way that a surface of the ruler where the scale lies faces towards the levelness measuring instrument and a lengthwise direction of the ruler is perpendicular to an upper surface of the first arm, and a reading indicated by the ruler at this time is observed via the levelness measuring instrument, which reading is recorded as a first reading. Then, the ruler is moved to a rear end of the first arm, and a reading indicated by the ruler at this time is observed via the levelness measuring instrument, which reading is recorded as a second reading. Next, the ruler is moved to a front end of the second arm, and a reading indicated by the ruler at this time is observed via the levelness measuring instrument, which reading is recorded as a third reading. Then, the ruler is moved to a rear end of the second arm, and a reading indicated by the ruler at this time is observed via the levelness measuring instrument, which reading is recorded as a fourth reading. The front end of each of the first arm and second arm is the end of the arm away from the base, and the rear end of each arm is the end of the arm close to the base. Whether the robot's arms are in a horizontal state is determined from whether the first indication, the second indication, the third indication and the fourth indication are equal.
There are at least the following problems with the prior art: in detection of the levelness of the robot's arms by the levelness measuring instrument, a ruler has to be used, and moved on the robot's arms, such that operations are complicated and manual measuring errors might be incurred.